WIRE DRAWING: PROCESS, TYPES AND APPLICATIONS - CULTURE VOCABULARY - 2025

The drawing is wire drawing by stretching rod cold. The most common materials in wire drawing are steel, aluminum and copper. However, wire drawing is applicable to any ductile metal or alloy; that is, it is capable of deforming without breaking under the action of a force.

The rod that gives rise to the wire is greatly reduced by passing it through a conical shaped hole called a wire, row, or die. That is the origin of the name of this procedure.

After threading the rod into a die located at one end of the assembly, the remaining end is linked with a block, attached to an electric motor that exerts traction on the rod. The rod reduces its diameter and increases its length.

If they are fine wires, the drawing machine must have several blocks, since the elongation of the wire must not occur in a single phase.

Wire drawing process

The drawing consists of the elongation of the wire while it is cold. In addition to reducing the diameter of the rod and increasing its length, this process also improves the mechanical characteristics of the material.

The process varies according to the dimensions of the metal bar that will be drawn. However, roughly the procedure consists of the execution of the following phases:

Proprietary

It is a pre-treatment of thermal conditioning that consists of subjecting the wire to temperatures above 900 ° C.

Immediately afterwards, the wire is rapidly cooled by applying a lead bath, in which its temperature is lowered by approximately 400 ° C.

The purpose of this first phase of the process is to enhance the ductility of the metal rod. Thanks to this property, the drawing process is viable.

Stripping

In this phase, the oxide and any external coating that is present on the rod, such as rust or laminations, is removed.

This process is carried out by means of chemical washes that are rinsed with water under pressure.

Drawing

This is the neuralgic phase of the process and consists of the transformation of the metal rod. Generally, the drawing is done in several blocks to guarantee the integrity of the process. For this, the wire drawing machine has several traction drums or coils.

Said traction coils guide the passage of the wire through the rows arranged for it, creating the blocks or processing stations.

In turn, each row has powdered lubricants, and the traction coils usually have air and water-based cooling mechanisms.

The final dimensions of the wire may vary depending on the diameter and length of the original bar, coupled with the design of the drawing machine.

For example, if the bar is 15 millimeters in diameter or more, the wire passes through the drawing stations several times to remove excesses and improve the surface finish of the wire.

For wires with smaller diameters, the previous procedure is repeated, with some intermediate heat treatments to change the physical properties of the wire and eliminate stiffness.

Sometimes, depending on the diameter of the bar, in each pass it is possible to reduce said diameter by up to 45%, until the wire is obtained with the desired characteristics.

This increases the tensile strength but to the detriment of the flexing of the material. Therefore, it is recommended to handle each step through the drawing machine with moderation.

Finish

At the end of the previous step, the wire must be straightened to eliminate the stresses inherent in the process. Sometimes thermal treatments are even applied to enhance the physical and mechanical properties of the final product.

Types

The wire drawing process can be carried out in three different ways, depending on the characteristics of the final product.

This implies that, depending on the machinery and the heat treatments used, the drawing result can be: a fine wire, a metal rod or a tube. The three main types of wire drawing are explained below.

Wire drawing

It consists of obtaining fine wire from the deformation of a rod. As previously described, this is possible by cold stretching of the metal, to take advantage of ductility.

For this type of process, the dies are made with cooled cast iron, diamond or tungsten carbide, to guarantee the effectiveness of the dies.

Rod drawing

In this case, the diameter of the final product is considerably larger than that of wire drawing. Consequently, the wire drawing machine used must be considerably more robust.

The main difference between wire drawing and rod drawing is that the wire can be wound around the pull coils. Instead, the rods should be kept straight.

To facilitate the processing and transfer of the rod after drawing, it is cut into sections according to the lengths of convenience.

Tube drawing

In this case, the result obtained from the drawing process is a tubular product. Broadly speaking, the procedure is similar to the previous cases, with the exception that the machinery is heavier.

To mold the thickness and diameter of the metal tubes, a mandrel is used; that is, a special press to hold the tubes as they are being processed.

The metal tube is transported through a system of bearings to facilitate the processing of the parts.

Applications

Wire drawing is used in the production of aluminum, copper and steel wires, among other materials. This material is highly valued in the field of electrical installations.

Very thin wires - generally made of molybdenum and tungsten, and with diameters less than 0.01 millimeters - are used in electronic applications.

In the case of metal rods and tubes, these types of elements are used in the construction, electrical installations and plumbing industries.

References

1. Curley, R. (2009). Wire drawing. Encyclopædia Britannica, Inc. London, England. Recovered from: britannica.com
2. Wire drawing (2010). Recovered from: wiki.ead.pucv.cl
3. Types of Drawing Process: Wire Drawing, Rod Drawing and Tube Drawing (2017). Recovered from: mech4study.com
4. Wikipedia, The Free Encyclopedia (2018). Wire drawing. Recovered from: es.wikipedia.org
5. Wire drawing (2017) TOKUSAI TungMoly Co., LTD. Recovered from: tokusai.co.jp